Dust dislodging system for electrostatic precipitators



Dec. 16, 1969 M L, GLAESER ETAL 3,483,659

DUST DISLODGING SYSTEM FOR ELECTROSTATIC PRECIPITATORS Filed Sept. 13, 1965 2 Sheets-Sheet l f@ ,W f6 1w vr: "[7 afs:- I 2L 2/\ /7 /7 I y, f/4 l i ab BY BAEL L. WILSON DeC- l5, 1969 M. 1 GLAESER ET AL 3,433,559

DUST DISLODGING SYSTEM FOR ELECTROSTATIC PRECIPITATORS Filed Sept. 13, 1965 l2 Sheets-Sheet 2 INVENTORS FIG. 2

MELv/N L. @LA/555,? d

BY EARL L, W/LSGN United States Patent O 3,483,669 DUST DISLODGING SYSTEM FOR ELECTRO- STATIC PRECIPITATORS Melvin L. Glaeser, Baltimore, and Earl L. Wilson,

Towson, Md., assignors to Koppers Company,

Inc., a corporation of Delaware Filed Sept. 13, 1965, Ser. No. 486,632 Int. Cl. B03c 3/76, 3/34 US. Cl. 55-112 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to electrostatic precipitators and more particularly to an improved system for removing dust accumulations within the precipitator.

Conventional electrostatic precipitators utilize a dual electrode system comprising active or discharge electrodes and passive or collector electrodes. Usually the active electrodes are equally spaced between the passive electrodes and are supported by a structural member joined to an insulator between the support member and the precipitator shell. The support member can be a metal channel, angle or other appropriate shape and is usually also used to conduct high voltage from a power source to the active electrodes. The passive electrodes are likewise supported by structural members resiliently joined to the precipitator shell and grounded thereto.

In operation, a high voltage potential is built up between the active and passive electrodes. The potential results in a corona discharge surrounding the active electrodes so that particulate matter or dust entrained in a gas directed past the electrodes assumes a static electrical charge and is thus attracted to the passive electrodes. Periodically, the electrodes and supporting structure are vibrated or rapped to dislodge the collected dust which falls into a collection hopper.

Conventionally, the electrode rappers are joined to the electrode support structure so that dust is dislodged frequently and normally large deposits do not accumulate. The magnitude of vibration usually required to dislodge even the dust accumulations on the support structure is so great that structural failures are often induced in the support structure. If the dust is permitted to remain on the support structure, it tends to bridge the clearance between the active and passive electrode systems causing arcing of voltage between them. When this occurs, the voltage controls of the precipitator will automatically reduce the voltage potential thus reducing the collection eiiiciency of the precipitator.

Certain dusts are naturally tenacious; while other dusts become tenacious due, for example, to condensation of moisture in the gas. Consequently, such dust tends to build up on horizontal at surfaces such as the tops of the passive electrodes and support structure. When dust accumulates to such extent that the angle of repose is exceeded, it falls off and becomes re-entrained in the gas thus reducing the collection eiciency of the precipitator. The conventional vibration discussed above is not suicient to dislodge this tenacious dust.

r"ice Accordingly, an object of the present invention is to provide a means for reducing and dislodging dust accumulations on the electrode support structure without inducing structural failures in the electrode support structure.

This invention contemplates the provision of auxiliary members overlying the flat top surfaces of the electrode support structure, a rapping system for vibrating the auxiliary members to dislodge any dust tending to accumulate thereon. The auxiliary members have surfaces nclined to the horizontal such that the angle of repose of the dust is exceeded thus retarding accumulation.

In one aspect of the invention an inverted structural angle overlays the top surface of a center support for the passive electrodes or collector plates. The center support is joined to the electrostatic precipitator shell in a coriventional manner and is not vibrated. Vibration is induced in the structural angle by a rapping source, joined to the precipitator shell and energized from a suitable power supply. The structural angle is mounted so that its apex forms a cone with the flat top surface of the center support which it overlies. Joined to and extending from the structural angle are rod-like fingers spaced apart so as to overlay the top surfaces of the collector plates. The ends of the ngers and the structural angle are loosely guided so that vibration `induced therein dislodges dust accumulated on them without the vibration being transmitted to the electrode support structure. The inclined surfaces of the structural angles inhibit accumulation of dust and the vibration dislodges whatever dust accumulates.

The above and further objects and novel features of the invention will appear more fully from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

In the drawings wherein like parts are marked alike:

FIGURE l is a schematic illustration of an elevational View of the novel precipitator in partial cross section;

FIGURE 2 is an isometric view ofthe novel precipitator of FIG. 1 with portions removed;

FIGURE 3 is a schematic illustration of an elevational view in partial cross-section of another embodiment of the invention;

FIGURE 4 is a section view taken along the line A-A in FIG. 3.

Referring to FIG. 1, a high voltage electrical potential from a suitable source (not shown) is applied to active electrode 18 and passive electrode 10. The resulting corona discharge causes the particles in the gas passing the electrode to assume a static charge and be attracted to the passive or collector electrode 10.

As illustrated in FIGS. l and 2, the passive electrode system comprises a plurality of passive electrodes or collector plates 10 suspended from lateral supports 11 and 12 by means of clips 13 securely joined to the collector plates. Center support 12 is integrally joined and grounded to the precipitator housing or shell 14 such as by welding or bolts (not shown). Lateral supports 11 are resiliently mounted to the shell 14 by firm connection to hanger rods 1S extending through the shell. The portion of the hanger rod exterior to the shell is firmly connected to a vibration source or rapper 16. The rapper is resiliently connected to the shell by means of a compession spring 17 located between the rapper and the shell. It is particularly advantageous to use the system as more particularly described in column 2, lines 1 26 in the patent to J. W. Pennington No. 3,030,753.

The active or discharge electrode system comprises a plurality of electrodes 18, preferably of wire-like configuration, connected to and suspended from a support member 19. The support member is conveniently made of steel angle and is resiliently mounted to the shell 14 by firm connection with hanger rods extending through the shell. The portion of the hanger rod 20 exterior to the shell is firmly connected to a rapper 16. The rapper is resiliently connected to the shell by means of a compression spring 17 placed intermediate to the rapper and an insulator 21 secured to the shell so that the voltage supplied to the discharge electrodes through the support member 19 is not grounded to the shell. This connection is advantageously made in accordance with the aforementioned patent to Pennington.

This conventional structure has had the problem that dust will accumulate on the top surfaces of the structural members which support the electrodes. In addition, dust will accumulate on the top surface of the collector plates. Conventional rapping of the electrodes is not sufficient to remove all of the dust accumulation. Increasing the magnitude of vibration may induce structural failure in the structural support system especially in the center support which usually is joined directly to the precipitator shell. This problem becomes particularly acute when the dust is tenacious due to its inherent characteristics, moisture or the like. In accordance with this invention, the problem is overcome by provision for inhibiting such accumulations and removing any accumulations that do occur.

As best illustrated in FIGS. l and 2, the novel improvement comprises an inverted structural angle 22, loosely guided by lugs 23, on the top surface of center support 12. A driving rod 24 is firmly joined, such as by welding, to the structural angle 22 and extends beyond the ends of the angle a sufficient distance to permit its being journaled in the shell. A plurality of rod-like fingers 25 are firmly joined to the structural angle 22 and are spaced apart so that they overlay the top surfaces of the collector plates 10. The ends of the fingers opposite the structural angle are formed into loops or eyes 26 which are loosely fitted over upright pins 27 securely joined to supports 11. Thus, top surfaces are provided which inhibit the accumulation of dust because they are inclined with respect to the horizontal top surfaces of the support members and collector plates.

Since some dust may nevertheless accumulate, a supplemental rapping system is provided for vibrating the abovementioned inclined surfaces to dislodge such accumulation of dust. The driving rod 24 extends through one wall of the shell and is firmly connected to a rapper 28 which is joined to the shell in the same manner as the rappers 16 for the active and passive electrodes.

In operation, a high voltage potential is maintained between the active electrodes 18 and the passive electrodes 10 in the known manner. As the gas to be cleaned is directed through the precipitator, dust entrained therein assumes a static charge of the same polarity as the active t electrode. The charged particles are thus attracted to the vertical surfaces of the collector electrodes. Periodically, the collector electrodes 10 are vibrated by the rappers 16 thus dislodging the collected dust which falls into collector hoppers (not shown) below the electrodes. Some of the dust is attracted to the inclined surfaces, for example surface 22S, overlying the support members, a part of which will fall olf the inclined surfaces due to gravity. Any remaining dust is dislodged by rapping the inclined surfaces by energizing the supplemental rapper 28. Rapper 28 is conveniently connected to the energization system of the conventional rappers so that it is energized at the same time. If desired, a separate energization system for rapper 28 may be provided which would actuate the rapper in a different sequence of operation than the conventional rappers.

In the embodiment of the invention as illustrated in FIGS. 3 and 4, advantage is taken of the conventional rapper system of the precipitator to vibrate the inclined surfaces. Inverted structural angles 22 and 30 are provided in overlying relationship to the lateral collector supports 11 and 12. The structural angles 30 are securely joined. such as by welding, to the outboard supports 11. The structural angle 22 overlying the center support 12 is loosely guided as hereinbefore described. Fingers 31 are spaced in overlying relationship to the collector plates 19 and their ends 35 are securely joined to the inverted angles 22 and 30. Thus, an integral assembly of inclined surfaces is provided so that as the conventional system of rappers 16 is energized, the inclined surface assembly in vibrated. If desired, the support 29 for the wire electrodes 18 may be an angle inverted as illustrated in FIG. 4. Thus, an inclined surface is provided which will tend to inhibit the accumulation of dust and will dislodge accumulated dust when vibrated by the wire electrode rappers.

We claim:

1. An electrostatic precipitator comprising:

a shell;

a plurality of active electrodes;

a plurality of passive electrodes forming lanes within said shell for the passage of gas therebetween, said active electrodes spaced along said lanes between said passive electrodes;

first support means connected to said shell for supporting said passive electrodes along the horizontally extending top portions thereof within said shell;

second support means insulated from said shell for supporting said active electrodes along the top portions thereof within said shell;

said electrodes adapted to have an electrical potential applied thereto whereby most of the particles entrained in the gas passing said electrodes are collected lon said passive electrodes but some of the particles tend to collect on the top portions of said electrodes and said support means;

a first inhibiting member overlying the top of said first support means comprising an L-beam the legs ot' which are inclined at substantially 45 or more with respect to said horizontally extending top portions with the apex formed by the juncture of said legs disposed above said top for inhibiting the accumulation of particles thereon;

a second inhibiting member overlying the top of each of said passive electrodes comprising a rod-like finger for inhibiting the accumulation of particles thereon:

said second support means including an L-bearn the legs of which form an angle of substantially 45 or more with respect to horizontal with the apex formed by the juncture of said legs disposed above said active electrodes; and

means for rapping said support means and said electrodes for dislodging particles accumulated thereon.

2. An electrostatic precipitator for removing particles from a gas comprising:

active and passive electrodes;

support means for supporting said electrodes along the tops thereof including a center support having a horizontally extending top surface and outer supports for said passive electrodes;

a shell for housing said electrodes and support means therein, said support means connected to said shell;

said passive electrodes forming lanes within said shell for the passage of gas therebetween, said active electrodes spaced along said lanes between said passive electrodes;

inhibiting surfaces overlying the top of said center support comprising an L-beam the legs of which are inclined at substantially 45 or more with respect to the top surface of said center support with the apex formed by the juncture of said legs disposed above said top;

a plurality of fingers secured to said L-beam in spaced relation so as to overlie the top surfaces of said passive electrodes, said fingers being pivotably joined to an outer support;

lvibrating said rod;

whereby said rapping means vibrates said rod and said L-beam and fingers secured thereto so that any particles clinging thereon are discharged.

References Cited UNITED STATES PATENTS Wintermute 55-112 Engelman 55--112 Meston 55-112 Wintermute 55-112 Roberts et al. 55-112 Sohlman et al 55-112 6 7/1959 Egan 55-112 1/1960 Drenning et al 55-112 X 5/1961 Drenning 55--112 4/ 1962 Pennington 55-112 7/ 1944 Hamilton 55-148 X 3/1953 Andres 55-148 X FOREIGN PATENTS 10/ 1927 Germany.

11/1927 Germany.

3/1932 Great Britain.

HARRY B THORNTON, Primary Examiner 15 DENNIS E. TALBERT, IR., Assistant Examiner U.S. Cl. X.R. 

